1. Field of the Invention
The present invention relates to an apparatus for fabricating a semiconductor device, and more particularly to an apparatus for heating gases for a semiconductor device that heats gases, which are introduced to a thin film forming device, an oxidation device, an etching device or a reaction furnace, to a fluid state.
2. Description of the Conventional Art
In a semiconductor device such as a thin film forming device or an etching device for fabricating a semiconductor device, a main gas which is a process source (a fluid substance participant of reaction on a wafer) and subsidiary gases such as a carry gas which carries the process source to a reaction furnace and an oxygen gas are introduced into a vaporizer (not shown), respectively maintaining a temperature under 100.degree., mixed and vaporized therein, then injected as the gaseous state into a chamber through a gas injector 1, and activated by receiving a heat energy or other energy on a wafer W, thereby having a reaction. Numerals 2 and 3 in FIG. 1 are a heat supplying unit and a gas discharge line, respectively.
When forming a thin film using the thin film forming device shown in FIG. 1, it is desirable to maintain a temperature of the wafer to be low and to increase a deposition rate of the thin film. To satisfy such requirements, support in various ways is necessary in the aspect of a hardware of a semiconductor device, and one of the various ways therefor is to introduce a gas in a heated state into the reaction furnace.
When the process sources, the main gases of the reaction, are required to be heated, there is provided a method of heating a process source tank, in which the process sources are stored, and also introducing the process gases, which are in a heated state at a temperature of about 100.degree. C. or below, into the reaction furnace by winding a heater at an outer wall of a tube which is a transfer path of the process source. Among various types of conventional methods of heating a tube, following three types are the most typical methods thereof.
A first type employs a method of heating a gas tube by simply winding a heater at an outer wall of a tube up to 300.degree. C.
As shown in FIGS. 2A and 2B, a second type of the tube heating method is to supply the heat energy to a fluid substance with a small space, wherein the fluid substance is heated while flowing in a tube 20 by winding a heater 21 at an outer wall of the spring-type heater 21.
As shown in FIG. 3, for a third type of the tube heating method, there is provided a heating vessel 31 disposed in a middle of a tube 30 and a small heating bottle 32 installed in the heating vessel 31, for thereby heating a gas in a direct contact method, the tube 30 and the heating vessel 31 being connected with a flange 33.
Now, the heating operation of the conventional art will be described.
In the heating operation employing the first type, a fluid heater maintains or heats a temperature of a process source gas with indirect heating through the tube by winding the heater at the tube to supply the heat energy to a fluid substance which flows in the linear tube.
In the heating operation employing the second type, the band heater 21 is provided at the outer wall of the spring-type role tube 20, thereby heating the process gas using the relatively small space. Here, the heating method applied in the second type is an indirect heating method in which the heat energy produced in the band heater 21 is transmitted to the roll tube 20 and then to the process source.
Lastly, the heating operation of the third type employs the heating device of an in-line type, in which the process source is introduced into the heating vessel 31 from the tube 30, so that the process source is heated while passing through the heating bottle 32 and then flows into a reaction furnace through the tube 30.
However, the conventional process source heating methods using the tube have problems.
The method of indirectly heating the process source flowing in the tube such as in the first or second type has a problem in that since the process source is heated through the tube which is a heat transmitting medium, temperature gradient of the process source can be incurred and uniformity of the temperature of the process source is poorly achieved. Also, there is another problem in which the maximum heating temperature is limited at about 300.degree. C. Thus, it is required to develop a hardware apparatus which uniformly controls the temperature of the gas, improves heat efficiency of the heater, and increases the maximum heating temperature.
Also, when applying the tube heating method of the third type, it is possible to solve the problem in which the maximum heating temperature is low in the first and second types due to the indirect heating method. However, the temperature uniformity is poorly achieved because of temperature difference the process source which flows contacting the heating bottle in the heating vessel and the process source which flows at a wall side of the heating vessel without directly contacting the heating bottle.